Answer:
In your lungs, the main airways (bronchi) branch off into smaller and smaller passageways -the smallest, called bronchioles lead to tiny air sacs (alveoli)
the bronchiole end in tiny air sacs called alveoli, where oxygen is transferred from the inhaled air to the blood, after absorbing oxygen, the blood leaves the lungs and is carried to the heart, the blood then is pumped through your body to provide oxygen to the cells of your tissues and organs.